In the original story treatment for Halloween H20, the sequel introduced Dr. Loomis' daughter, only to abruptly kill her off in the first act.

Halloween H20 was the first Halloween movie to retcon prior entries, but the original script contained a scene which kept Jamie Lloyd canon.

Michael Myers' mask in Halloween has become an iconic image for the entire franchise. Why did Halloween H20 get it so wrong?

Janet Leigh's meta cameo in Halloween H20: 20 Years Later is a self-referential acknowledgment of her role as Marion Crane in Psycho.